Intangible Assets and Goodwill (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Customer Relationships [Member]	Dec. 31, 2011 Customer Relationships [Member]	Sep. 30, 2012 Supplier Relationships [Member]	Dec. 31, 2011 Supplier Relationships [Member]	Sep. 30, 2012 Software And Technology [Member]	Dec. 31, 2011 Software And Technology [Member]	Sep. 30, 2012 Trademark And Trade Name [Member]	Dec. 31, 2011 Trademark And Trade Name [Member]	Sep. 30, 2012 Noncompete Agreements [Member]	Dec. 31, 2011 Noncompete Agreements [Member]	Sep. 30, 2012 Total Intangible Assets [Member]	Dec. 31, 2011 Total Intangible Assets [Member]
Finite lived intangible assets
Finite lived intangible assets, gross					$ 406,746,000	$ 409,489,000	$ 29,000,000	$ 29,000,000	$ 168,912,000	$ 170,286,000	$ 34,844,000	$ 33,908,000	$ 7,487,000	$ 7,564,000	$ 646,989,000	$ 650,247,000
Finite lived intangible assets accumulated amortization					(260,737,000)	(237,536,000)	(21,387,000)	(19,213,000)	(149,360,000)	(143,456,000)	(32,101,000)	(30,076,000)	(7,409,000)	(7,363,000)	(470,994,000)	(437,644,000)
Finite lived intangible assets, net					146,009,000	171,953,000	7,613,000	9,787,000	19,552,000	26,830,000	2,743,000	3,832,000	78,000	201,000	175,995,000	212,603,000
Finite Lived Intangible Assets Amortization Expense	$ 10,000,000	$ 14,000,000	$ 35,000,000	$ 43,000,000